Cosmetic hair and skin-care emulsions are expected by the consumer to satisfy a number of requirements. Apart from the cleansing and caring effects which determine the particular application, importance is attributed to such diverse parameters as highest possible dermatological compatibility, good lipid-layer-enhancing properties, elegant appearance, optimal sensory impression and shelf life.
Besides a number of surfactants, cosmetic hair- and skin-care preparations generally contain, above all, oil components and water. The oil components (emollients) used include, for example, hydrocarbons, ester oils and vegetable and animal oils/fats/waxes. In order to satisfy stringent market requirements in regard to sensory properties and optimal dermatological compatibility, new oil components and emulsifier mixtures are being continuously developed and tested. The use of ester oils in cosmetic products has been known for some time. Because of their importance, new processes for their production are also being continuously developed. Branched ester oils in particular impart a “lighter” skin feel and are therefore the subject of intensive research. The use of 2-methyl-1,3-propanediol monoesters is described, for example, in DE 101 60 681; the use of 2-methyl-1,3-propanediol diesters is described in DE 101 60 682. U.S. Pat. No. 2,921,089 describes di-(2-propylheptyl)-phthalate and its suitability as a plasticizer for PVC. EP 1 415 978 A1 (Oxeno Olefinchemie GmbH) describes mixtures containing benzoic acid-2-propylheptyl ester and the use of these mixtures as plasticizers for polymers, PVC or PVC plastisols and also their use in paints and lacquers, adhesives, adhesive components and sealing compounds.
The problem addressed by the present invention was to provide new ester oils preferably liquid at 20° C. for cosmetic applications which would have an improved profile in regard to their sensory properties (lightness, non-greasy skin feel, softness, spreadability, absorption, distribution behavior, oiliness) and which could be incorporated in a number of cosmetic formulations. The hydrolysis stability of the esters and their capacity for formulation at low pH values would also be of interest in this regard. In addition, the esters would lend themselves to incorporation both in w/o and in o/w formulations and would be compatible in particular with crystalline UV filters, pigments, antiperspirants, salts and silicones. It has surprisingly been found that esters of 2-propylheptanol lead to sensorially light products. Some of these esters and their production are known from DE 103 05 562, but for a totally different application, namely as polymer additives. WO 2006/097235 describes esters of 2-propylheptanol with linear or branched carboxylic acids. Unfortunately, these esters are problematic in the formulation of preparations containing UV filters. Above all, the unsatisfactory solubility of the UV filters is a limiting factor.
Accordingly, the problem addressd by the present invention was to provide esters that would be improved in relation to the prior art, more particularly esters which could readily be formulated together with UV filters and, at the same time, would not have any disadvantages relative to the prior art in regard to sensory impression.